Method and device for contactless measurement of a linear textile formation such as yarn etc

ABSTRACT

The invention relates to the contactless measurement of a linear textile formation such as yarn ( 1 ), thread, textile fibre, sliver, etc. in which a linear textile formation moves in a radiation flux ( 7 ) between a radiation source ( 3 ) and a radiation sensor ( 4 ) consisting, of a plurality of radiation-sensitive elements ( 40 ) arranged next to each other in at least one row and in which the diameter and/or the hairiness and/or the density of the linear textile formation is determined on the basis of the number of overshadowed radiation-sensitive elements ( 40 ) of the radiation sensor ( 4 ) and/or on the basis of the irradiation degree of the radiation-sensitive elements ( 40 ). In order to measure a high degree of the total length of the moving textile formation it is proposed to match the dimensions of the radiation-sensitive elements ( 40 ) such that the dimension of the radiation-sensitive elements ( 40 ) of the radiation sensor ( 4 ) in the direction of the motion of the measured linear textile formation is superior to their dimension in the direction normal to the direction of the motion of the measured linear textile formation.

TECHNICAL FIELD

[0001] The invention relates to a method of contactless measurement of a linear textile formation such as yarn, thread, textile fibre, sliver, etc. in which a linear textile formation moves in a radiation flux between a radiation source and a radiation sensor consisting of a plurality of radiation-sensitive elements arranged next to each other in at least one row and in which the diameter and/or the hairiness and/or the density of the linear textile formation is determined on the basis of the number of overshadowed radiation-sensitive elements and/or on the basis of the irradiation degree of the radiation-sensitive elements.

[0002] The invention also relates to a device for carrying out the method containing a radiation source and a radiation sensor consisting of a plurality of radiation-sensitive elements arranged next to each other in at least one row.

BACKGROUND OF THE INVENTION

[0003] There are known methods of contactless measurement of a linear textile formation such as yarn, thread, textile fibre, sliver, etc. in which a linear textile formation moves in a radiation flux between a radiation source and a radiation sensor consisting of a plurality of radiation-sensitive elements arranged next to each other in a row and in which the diameter and/or the hairiness and/or the density etc. of the linear textile formation is determined on the basis of the number of overshadowed radiation-sensitive elements. For carrying out these methods, radiation sensors used are CCD sensors sensing the linear textile formation discontinuously in very short sections, each of about 10 μm of its length.

[0004] The drawback of these methods consists in that as a matter of fact only a minimum of the total length of the linear textile formation is really measured and that the values determined on said very short sections of the measured linear textile formation, for instance when measuring yarn thickness, have to be integrated in a complicated way prior to the processing proper in order to eliminate or at least to minimize the influence of coincidental events arising during the measurement of very short sections of the linear textile formation and so to achieve the required measurement precision of the parameters of the linear textile formation. This is due to the fact that the yarn moves at a given velocity such as 1 m.s⁻¹ whereas the current sensing velocity of the linear textile formation by means of CCD sensors is about 1× in 1 ms. Since the radiation-sensitive elements of CCD sensors used for contactless measurement of a linear textile formation are about 10 μm×10 μm in size, these measurement methods, when applied to a linear textile formation moving for instance at 1 m.s⁻¹ effectively manage to measure as little as 1% of the total length of the linear textile formation which especially nowadays has proved to be insufficient.

[0005] For this reason, the invention intends to develop a more exact method of contactless measurement of a linear textile formation permitting virtually to measure a larger part of the length of the linear textile formation in relation to the total length of the linear textile formation and at the same time to permit a simpler processing of the measurement results.

PRINCIPLE OF THE INVENTION

[0006] The aim of the invention has been reached by a method of contactless measurement of a linear textile formation such as yarn, thread, textile fibre, sliver, etc., whose principle consists in that in each row of radiation-sensitive elements the information on the properties of the measured linear textile formation is at a given measurement instant determined on a length section of the linear textile formation whose length is, on the one hand, superior to the dimension of radiation-sensitive elements of this row of radiation-sensitive elements in the direction normal to the direction of the motion of the linear textile formation and, on the other hand, inferior to the length of the smallest defect required to be detected of the linear textile formation, thus, on the one hand, obtaining the virtual measurement of a greater portion of the measured linear textile formation while maintaining the measurement velocity and, on the other hand, dispensing with the necessity of integrating individual values determined by the radiation sensor during the measurement of the thickness of the linear textile formation and thus simplifying the processing of the measurement results.

[0007] The advantage of the invention consists in the fact that the measurement proper of the linear textile formation, i.e., without the subsequent integration of the individual values found by measurement, furnishes a value which by its character better reflects the actual parameters of the measured linear textile formation. This permits to increase the processing speed of individual measurements and to simplify the calculation algorithms for evaluating the measurement and interpreting the measurement results, thus reducing the requirements put on the device for measurement evaluation.

[0008] The principle of the device for carrying out the method of contactless measurement of a linear textile formation such as yarn, thread, textile fibre, sliver, etc., consists in that the dimension of the radiation-sensitive elements of the radiation sensor in the direction of the motion of the measured linear textile formation is superior to their dimension in the direction normal to the direction of the motion of the measured linear textile formation.

[0009] The device arranged in this way is easy to produce and to control, reliable in operation, and sufficient in precision. Another advantage of this device consists in the increased surface of the radiation-sensitive elements of the radiation sensor as compared with the radiation-sensitive elements of up to now used radiation sensor. This reduces the sensitivity of the radiation sensors to negative influences due to dust and permits better to define the base point of the radiation-sensitive elements if such a base point exists and is required. Another advantage of this device consists in the increased surface of the radiation-sensitive elements of the radiation sensor as compared with the radiation-sensitive elements used up to now thus increasing the sensitivity of the radiation sensor. Due to the increased sensitivity of the radiation sensor, the radiation sensor equipped with rectangular radiation-sensitive elements permits at a given irradiation intensity to measure higher speeds than the radiation sensor equipped with square radiation-sensitive elements (i.e. square in plan view). In one preferred embodiment, the radiation sensor is made as a CMOS optical sensor.

[0010] In another preferred embodiment, the radiation sensor consists of a CCD sensor.

[0011] Each of the two types of the radiation sensor is sufficiently precise and reliable for the method according to the invention. The advantage of the CMOS optical sensors over the CCD sensors consists in the more favourable measurement speed, in a more suitable and therefore more easily processable output signal, easier manufacture, and lower purchase cost. However, in spite of some drawbacks of the CCD sensors as compared with the CMOS optical sensors, the device equipped with the CCD sensor is sufficiently reliable and fully operative.

[0012] For obtaining the required measurement precision with sufficiently small size of the radiation-sensitive elements, it is advantageous if the radiation-sensitive elements are shaped as rectangular with dimensions in the direction of the motion of the measured linear textile formation between 15 μm and 200 μm.

[0013] From the point of view of simplicity of the arrangement of the device for the contactless measurement of the linear textile formation with sufficient measurement precision and simplicity of processing of the signals of the radiation sensor it is advantageous if the radiation sensor contains one row of radiation-sensitive elements.

[0014] For obtaining high measurement precision involving, however, higher time consumption and higher requirements put on the device for the processing of the measured data, it is advantageous if the radiation sensor comprises at least two rows of radiation-sensitive elements with the neighbouring rows of radiation-sensitive elements mutually reset in the direction normal to the direction of motion of the measured linear textile formation.

[0015] From the point of view of optimizating the relation between the high precision of the measuring of the linear textile formation on the one side and the required amount of time consumption and requirements punt on the device for processing the measured data on the other side it is advantageous if the radiation sensor comprises exactly two rows of radiation-sensitive elements mutually reset in the direction normal (perpendicular) to the direction of motion of the measured linear textile formation by one half of their dimension in this direction.

DETAILED DESCRIPTION

[0016] Reference will now be made in detail to the presently presented embodiments of the invention, one or more examples of which are shown in the figures. Each example is provided to explain the invention, and not as a limitation of the invention. In fact, features illustrated or described as part of one embodiment can be used with another embodiment to yield still a further embodiment. It is intended that the present invention cover such modifications and variations.

[0017] The contactless measurement of a linear textile formation such as yarn, thread, textile fiber, sliver, etc., is carried out on various textile machine types such as open-end spinning machines, winding machines, etc.

[0018] In the shown example of FIG. 1, the device for contactless measurement of a linear textile formation is used on an open-end spinning machine for measuring a yarn 1. However, the device can be suitably modified for use on other textile machines and for the measurement also of linear textile formations other than the yarn 1, such possible modification having no influence on the principle of the invention.

[0019] In the shown example of embodiment, the yarn 1 is drawn off from a spinning device 2 in the direction of the arrow 10 and is wound by a not illustrated winding device on a not illustrated bobbin. On its path between the spinning device 2 and the winding device, the yarn 1 passes through the space between a radiation source 3 and a radiation sensor 4. In the shown example of embodiment, the travel path of the yarn 1 is stabilized by a pair of guiding rollers 5. In other embodiments, the guiding of the yarn 1 in the space between the radiation source 3 and the radiation sensor 4 is ensured by other suitable means such as fix guides. In still another example of embodiment, no guiding elements are provided for guiding the yarn 1 in the space between the radiation source 3 and the radiation sensor 4.

[0020] In the shown example of embodiment, the radiation source 3 is made as a point source 30 of radiation of a suitable type such as LED, LASER, a bulb, etc. In a not shown example of another embodiment, the radiation source 3 can be of another suitable type such as a straight-line radiation source or even a flat radiation source.

[0021] In the shown embodiment, the radiation sensor 4, situated opposite the radiation source 3, contains one row of radiation-sensitive elements 40 situated next to each other. In another embodiment, the radiation sensor 4 contains at least two rows of radiation-sensitive elements 40 situated next to each other, and the total number of rows of the radiation-sensitive elements 40 situated next to each other can be even greater. However, between each two neighboring radiation-sensitive elements 40, there are sections (intervals) in which the measured linear textile formation cannot be followed, because the neighboring radiation-sensitive elements 40 are physically (materially) separated there. In standard measurements, the existence of these intervals is from the point of view of the measurement precision immaterial but, for extremely high precision requirements this drawback should be eliminated, for instance, by arranging the rows of the radiation sensor 4 with more than one row of radiation-sensitive elements 40 in the direction normal (perpendicular) to the direction of motion of the measured linear textile formation. Thus, for instance, in a radiation sensor 4 with two rows of radiation-sensitive elements 40 reset to each other and normal to the direction of motion of the measured linear textile formation, each row of the radiation-sensitive elements 40 senses the measured linear textile formation also in the above mentioned sections (intervals) between the radiation-sensitive elements 40 of the other row of the radiation-sensitive elements 40. This mutual reset preferably equals in size one half of the dimension of one of the radiation-sensitive elements 40 in the direction normal to the direction of motion of the measured linear textile formation. In the direction of the length of the row of the radiation-sensitive elements 40 the radiation sensor 4 is situated across the direction of motion of the measured linear textile formation such as the yarn 1, and the dimension of the individual radiation-sensitive elements 40 in the direction of motion of the measured linear textile formation, i.e., in the longitudinal direction of the linear textile formation, is superior to their dimension in the direction transverse to the direction of motion of the yarn 1, i.e., in the direction of the length of the row of the radiation-sensitive elements 40. However, the dimension of the radiation-sensitive elements 40 in the direction of motion of the measured linear textile formation is inferior to the length of the smallest defect of the measured linear textile formation required to be detected. From the point of view of the optimizing of the relation between the required measurement precision and the cost of the constituting elements of the measurement device, in particular of the radiation sensors 4, it is as a rule sufficient for the individual radiation-sensitive elements 40 to be sized between 15 μm and 200 μm in the direction of motion of the measured linear textile formation. The radiation sensor 4 can consist of a CMOS optical sensor or of a CCD sensor. Each of the rows of the radiation-sensitive elements 40 of the radiation sensor 4 is coupled with an evaluation device 6 of the state and/or degree of its irradiation. In a further embodiment, the evaluation device 6 can be made as an integral part of the radiation sensor 4. The measured linear textile formation, in the shown embodiment, the yarn 1, passes during the measurement through a radiation flux 7 emitted by the radiation source 3 and casts shadow on some of the radiation-sensitive elements 40 of the radiation sensor 4 as is in the shown example of embodiment marked by the dark surface 400 on the front side of the radiation sensor 4. The number of irradiated radiation-sensitive elements 40 and/or the degree of their irradiation serves as basis for determining in a suitable way the required parameters of the measured linear textile formation such as the yarn 1. In other words, the evaluation device 6 is able to evaluate the function of the radiation sensor 4 and is fitted with an output 60 of information on the monitored parameters of the measured linear textile formation such as the yarn 1, for instance, on the thickness of the yarn 1, or the hairiness of the yarn 1, etc. As required by specific needs of a given case, the output 60 can be connected with further information-processing devices including, for instance, a control system of the machine or the operating unit and/or a displaying device and/or a recording device and/or regulation means of the operating unit of the machine and/or control means of the operating unit, used to interrupt the moving yarn and/or to stop at least one of the functional elements of the operating unit of the machine, etc.

[0022] In another embodiment, the contactless measurement device for the linear textile formation can be fitted or coupled with a suitable device for controlling the radiation emitted by the radiation source 3 to more exactly control both the intensity of the radiation and, in discontinuous radiation source, the time course of the radiation.

[0023] The contactless measurement of the linear textile formation such as the yarn 1, thread, textile fiber, sliver, etc., takes place with the linear textile formation moving In the radiation flux 7 in the space between the radiation source 3 and the radiation sensor 4. The linear textile formation takes a part of the radiation flux 7 and thus casts shadow on intensity of the radiation and, in discontinuous radiation source, the time course of the radiation.

[0024] The method of contactless measurement of the linear textile formation such as the yarn 1, thread, textile fibre, sliver, etc., takes place with the linear textile formation moving in the radiation flux 7 in the space between the radiation source 3 and the radiation sensor 4. The linear textile formation takes a part of the radiation flux 7 and thus casts shadow on some of the radiation-sensitive elements 40 of the radiation sensor 4. At predetermined time intervals, the radiation sensor 4 carries out individual measurements of the linear textile formation, each time on a portion of the length of the linear textile formation as a rule superior to 15 μm. Consequently, if the measured linear textile formation moves at 1 m.s⁻¹ and the parameters of the linear textile formation are measured at a speed of 1× in 1 ms, each time on a length of the linear textile formation as a rule superior to 15 μm, this measurement method virtually covers at least 1.5% of the total length of the measured linear textile formation as compared with 1% obtained by the methods of the state of art at the same speed of measurement and of motion of the linear textile formation which represents an increase in the virtually measured length of the linear textile formation by at least 50% as compared with the same measurement carried out by existing methods and means. With larger dimensions of the radiation-sensitive elements 40 in the direction of motion of the measured linear textile formation, the above improvement on the virtual measurement of the length portion of the measured linear textile formation is still greater with all accompanying positive consequences. Thus for instance, if the radiation sensor 4 used for the measurement of a linear textile formation is fitted with radiation-sensitive elements 40 200 μm long in the direction of motion of the measured linear textile formation and if the measured linear textile formation moves at a speed of 1 m.s⁻¹ and the measurement speed is 1× in 1 ms a section of 200 μm is measured each time so that the virtual measurement of the parameters of the linear textile formation comprises 20% of its total length as compared with 1% currently reached at present at the same speed of both the measurement and of the motion speed of the measured linear textile formation. This is an increase by 2000% in the virtually measured length of the linear textile formation as compared with the same measurement carried out by existing methods measurement of the linear textile formation, the obtained values are further used in a suitable way for processing and/or displaying and/or evaluating the measurement and/or for interpreting the measurement results.

[0025] The device for contactless measurement of the linear textile formation such as the yarn 1, thread, textile fiber, sliver, etc., can be on each operating unit of the textile machine in question controlled by a control unit of the operating unit which can also evaluate and process the measured values of the parameters of the measured linear textile formation.

[0026] In case of a radiation sensor 4 fitted with matrix configuration of radiation-sensitive elements 40, the required surface of the radiation sensor 4 contains a smaller number of radiation-sensitive elements as compared with the presently used radiation sensors with square plain view profile of the radiation-sensitive elements which results in lower costs of the radiation sensor according to the invention as compared with the existing radiation sensors fitted with matrix configuration of radiation-sensitive elements. Such an arrangement permits the speeding up of the measurement due to the smaller number of radiation-sensitive elements 40 in the radiation sensor 4 according to the invention, because, in matrix sensors, the values measured by each radiation-sensitive element 40 are calculated separately. Although as a rule the matrix configuration of radiation-sensitive elements is from the point of view of the measurement speed and ease of processing of the output signal less suitable than a radiation sensor 4 fitted with one row of radiation-sensitive elements 40, there exist cases in which such configuration of the radiation-sensitive elements 40 is more advantageous than the single row arrangement.

[0027] It will be appreciated by those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope of the invention. It is intended that the present invention include such modifications and variations as come within the scope of the appended claims and their equivalents. 

1. A method of contactless measurement of a linear textile formation such as yarn, thread, textile fibre, sliver, etc. in which a linear textile formation moves in a radiation flux between a radiation source and a radiation sensor consisting of a plurality of radiation-sensitive elements arranged next to each other in at least one row and in which the diameter and/or the hairiness and/or the density of the linear textile formation is determined on the basis of the number of overshadowed radiation-sensitive elements and/or on the basis of the irradiation degree of the radiation-sensitive elements, characterized by that in each row of radiation-sensitive elements (40) the information on the properties of the measured linear textile formation is at a given measurement instant determined on a length section of the linear textile formation whose length is, on the one hand, superior to the dimension of radiation-sensitive elements (40) of this row of radiation-sensitive elements (40) in the direction normal to the direction of the motion of the linear textile formation and, on the other hand, inferior to the length of the smallest defect required to be detected of the linear textile formation, thus, on the one hand, obtaining the virtual measurement of a greater portion of the measured linear textile formation while maintaining the measurement velocity and, on the other hand, dispensing with the necessity of integrating individual values determined by the radiation sensor during the measurement of the thickness of the linear textile formation and thus simplifying the processing of the measurement results.
 2. A device for carrying out the method claimed in claim 1, comprising a radiation source and a radiation sensor consisting of a plurality of radiation-sensitive elements situated next to each other in at least one row, characterized by that the dimension of the radiation-sensitive elements (40) of the radiation sensor (4) in the direction of the motion of the measured linear textile formation is superior to their dimension in the direction normal to the direction of the motion of the measured linear textile formation.
 3. A device as claimed in claim 2, characterized by that the radiation sensor (4) is made as a CMOS optical sensor.
 4. A device as claimed in claim 2, characterized by that the radiation sensor (4) is made as a CCD sensor.
 5. A device as claimed in any of claims 2 to 4, characterized by that the radiation-sensitive elements (40) of the radiation sensor (4) are shaped as rectangulars with dimensions in the direction of the motion of the measured linear textile formation ranging between 15 μm and 200 μm.
 6. A device as claimed in any of claims 2 to 5, characterized by that the radiation sensor (4) contains one row of radiation-sensitive elements (40).
 7. A device as claimed in any of claims 2 to 5, characterized by that the radiation sensor (4) contains at least two rows of radiation-sensitive elements (40) with the neighbouring rows (40) of radiation-sensitive elements mutually reset in the direction normal (perpendicular) to the direction of motion of the measured linear textile formation.
 8. A device as claimed in claim 7, characterized by that the radiation sensor (4) comprises exactly two rows of radiation-sensitive elements (40) mutually reset in the direction normal (perpendicular) to the direction of motion of the measured linear textile formation by one half of their dimension in this direction. 